In recent years, semiconductor devices have been meeting a remarkable technological innovation.
In mobile information and telecommunication terminals such as smartphones and tablet computers, in order to enable high-speed processing of large volumes of information, semiconductor elements are multilayer connected by use of TSV (through-silicon via) technology, then flip chip bonded to an 8- to 12-inch silicon interposer, and sealed by a thermosetting resin together with the interposer on which the plurality of multilayer connected semiconductor elements are mounted. After polishing the unrequired cured resin on the semiconductor elements, division into individual chips is conducted, whereby a semiconductor device which is thin, small-sized, multifunctional and capable of high-speed processing can be obtained.
In the cases where such substrates as small-diameter wafers of approximately 8 inches are used, sealing and molding can be performed without serious problems. Where the diameter is at least 12 inches, however, the compressive stress of the epoxy resin or the like after sealing is so high as to bring about such a problem as peeling of the semiconductor element from the substrate made of metal or the like, which hampers transition to mass production. In order to solve the above-mentioned problem brought about attendant on the increase in diameter of the wafer and the metal substrate, it has been necessary to reduce the compressive stress at the time of curing by loading with at least 90% by weight of filler or by lowering the elasticity of the resin.
Where a silicon interposer is entirely sealed from above with a thermosetting resin, however, large warpage occurs due to a difference between silicon and the thermosetting resin in coefficient of thermal expansion. The large warpage makes it impossible to apply the intermediate product to the subsequent polishing step or individualizing step. This is a serious technical problem.
Further, in recent years, attendant on the trend toward multilayer stacking of semiconductor elements, the sealing layer has increased in thickness, so that semiconductor devices accompanied by thinning through polishing of the resin layer used for sealing have come to be the mainstream. When a sealing or encapsulating material of a filler loading of at least 90% by weight is used, a blade of a dicing apparatus is liable to be damaged at the time of polishing the resin layer used for sealing; as a result, the frequency of replacement of the blade is high, which causes a rise in cost. In addition, since polishing must be conducted at an enhanced polishing pressure, such problems as damaging of the semiconductor elements or cracking of the wafer itself have been occurring. On the other hand, where a low-elasticity resin material represented by conventional silicone compounds is used, such problems as clogging with the resin or cracking of the resin have been occurring at the time of polishing, due to the softness of the resin.
Note that examples of the background art related to the present invention include the following.